Mercury-Trapping Forests: How Pristine Landscapes Shape Mercury Burden on Wildlife

ISL senior scientists Drs Mrinalini Erkenswick Watsa, Gideon Erkenswick Watsa, and Caroline Moore have collaborated with a team of international researchers led by Dr. Jacqueline Gerson to understand the impact of mercury used in artisanal or small-scale gold mining (ASGM) on ecosystems both close to and far away from ASGM published in Nature Communications

Mercury Release
Mercury emissions from artisanal and small-scale gold mining throughout the Global South exceed coal combustion as the largest global source of mercury.
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Years of artisanal mining along the Madre de Dios River and its tributaries have left their marks, both seen and unseen. Miners, swarming to the region in a modern-day goldrush, have cleared away pockets of this sliver of the Peruvian Amazon. The hangover from the continuing boom has left behind the telltale moonscapes of barren land, muddied streams and rivers, and an invisible toxin that fouls the water, the air and, as a recent study has shown, the forests themselves. The study, published Jan. 28 in the journal Nature Communications, reveals that forests — and dense, intact forests in particular — sponge up mercury in the atmosphere that comes from gold mining in the Madre de Dios’s riverine soils. The mercury gathers on the surface of the leaves and in their tissues, and then rainfall washes it from high in the canopy to the forest floor, in a process that scientists call “throughfall.”

by John C. Cannon on 28 February 2022

This is particularly important for ISL’s first hub at the Los Amigos Conservation Concession, a protected piece of land where we have sampled from thousands of animals, including but not limited to, three species of primates (L. weddelli, S. imperator, and P. brunneus), at least 59 species of birds in 21 families, eleven genera of bats, seven genera of rodents, five genera of marsupials, and one genera of rabbit.  

The mercury is released into the air by miners searching for gold along nearby riverbanks. They use mercury to separate the precious metal from surrounding sediment and then burn it off. Carried in the air, particles catch on leaves like dust and are washed onto the forest floor by rain. Other particles are sucked into the leaves’ tissue. From there, mercury appears to have transferred up the food web to songbirds, which showed levels of mercury two to 12 times as high as those in comparable areas farther from mining activity.

By Catrin Einhorn on 28 January 2022

From “Alarming Levels of Mercury Are Found in Old Growth Amazon Forest published in The New York Times

That’s right, Los Amigos Conservation Concession had the highest levels of mercury in throughfall recorded anywhere in the globe. And this intense mercury burden in the forest seemed to have translated to the songbirds, which have 2-12 times higher mercury stored in their feathers compared to birds at Cocha Cashu, a protected forest upstream in Manu National Park. 

We are expanding this work by curating mercury data across species and time tested in feathers and fur at the Los Amigos Biological Station Wildlife Conservation Laboratory. This testing is being done at site with training of the laboratory’s Peruvian scientists.

Hub 1: Peru
Learn more about ISL and mercury testing in-situ at Los Amigos Wildlife Conservation Laboratory
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Hub 1: Peru
Learn more about ISL and mercury testing in-situ at Los Amigos Wildlife Conservation Laboratory
Click Here
Hub 1: Peru
Learn more about ISL and mercury testing in-situ at Los Amigos Wildlife Conservation Laboratory
Click Here
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